1. Field of the Invention
The present invention relates to a paper machine, and, more particularly, to a permeable belt used in a belt press in a paper machine.
2. Description of the Related Art
In a wet pressing operation a fibrous web sheet is compressed at a press nip to the point where hydraulic pressure drives water out of the fibrous web. It has been recognized that conventional wet pressing methods are inefficient in that only a small portion of a rollers circumference is used to process the paper web. To overcome this limitation, some attempts have been made to adapt a solid impermeable belt to form an extended nip for pressing the paper web to dewater the paper web. A problem with such an approach is that the impermeable belt prevents the flow of a drying fluid, such as air through the paper web. Extended nip presses (ENP) belts are used throughout the paper industry as a way of increasing the actual pressing dwell time in a press nip. A shoe press is the apparatus that provides the ability of the ENP belt to have pressure applied therethrough, by having a stationary shoe that is configured to the curvature of the hard surface being pressed, for example, a solid press roll. In this way the nip can be extended well beyond the limit of the contact between the press rolls themselves. An ENP belt serves as a roll cover on the shoe press. This flexible belt is lubricated on the inside to prevent frictional damage. The belt and shoe press are non-permeable members and dewatering of the fibrous web is accomplished by the mechanical pressing thereof.
What is needed in the art is a belt, which provides enhanced dewatering of a continuous web.